The invention relates to electro-coagulation of tissue of the body and to the performance of other modes of electrotherapy, especially within the body, via catheters.
As is known by those of skill in the art, radiofrequency energy of suitable current density and wave form to perform electro-coagulation (cauterization) may be used to seal potential hemorrhaging or bleeding areas by electro-coagulation of tissue and blood, without cutting. With this technique RF coagulation current applied to the tissue generates heat by resistive losses in the conductive tissue. The resulting heat drives out extracellular and intracellular water resulting in coagulation necrosis. Similarly, the technique is used to cause necrosis of (i.e. "ablate") tissue that is performing improperly, especially arrhythmic heart tissue.
One method of performing electrocoagulation of tissue is through the use of mono-polar electrodes, in which one electrode is carried by a catheter to the site while the other electrode is an exterior ground plate placed on the skin of the patient. In another method, a bipolar catheter is employed. An example is the Gold Probe.TM., manufactured by Boston Scientific Corporation, the assignee of the present invention. It comprises a flexible catheter with a distal tip formed of a ceramic cylinder having a hemispherical end. The ceramic tip includes a pair of gold spiral electrodes applied to its cylindrical surface and domed end. The spiral electrodes are separated by insulated areas in an arrangement resembling the stripes of a barber pole. RF current flowing between the electrodes heats and cauterizes the tissue which is contacted by the tip of the catheter. The catheter is constructed to be employed through the working channel of an endoscope to seal potential bleeding sites such as in the GI tract or the esophagus.
In another instance, RF coagulation catheters of other forms have been introduced through the vascular system to the heart to remedy arrhythmia. In this case electrophysiological evaluation is performed at locations on the heart, and when a site requiring treatment is found, the catheter is used to ablate or deaden the tissue to correct the arrhythmia.
Other forms of treatment to address bleeding sites or sites requiring ablation have included the use of catheter-placed needles that inject drug agents such as vaso-constrictors for reducing bleeding and absolute ethanol for ablation of tissue.
In these and similar instances of therapy the prior art has overlooked possibilities of improving the location, depth, degree and accuracy of control of the treatment and the possibilities of multi-modality treatment employing a single catheter.